One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,4,6)(3,5,7,8)(9,10,13,11)(12,15,16,14)(17,18,23,24)(19,20,21,22)(25,26)(27,30)(28,31)(29,34)(32,37)(33,35)(36,39)(38,40)(9,10,13,11)(12,15,16,14)(17,19,23,21)(18,20,24,22)(26,27)(28,35)(29,37)(38,39)(10,11)(14,15)(17,20,23,22)(18,19,24,21)(25,27,30,26)(28,33,35,31)(29,32,37,34)(36,38,40,39)(1,2)(3,5)(4,6)(7,8)(9,11,13,10)(12,15,16,14)(17,21,23,19)(18,20,24,22)(25,28,30,35)(26,31,27,33)(29,36,37,40)(32,38,34,39)(1,3,4,7)(2,5,6,8)(9,12)(10,14)(11,15)(13,16)(17,22,23,20)(18,19,24,21)(25,29)(26,32)(27,34)(28,36)(30,37)(31,38)(33,39)(35,40)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.